Hydraulic press system



Sept. 17, 1946. w, STEPHENS I 2,407,855

HYDRAULIC PRESS SYSTEM Filed April 15, 1945 2 Shets-Sheet. 1

/7 "11 W l ill/z P 1946- w. T. STEPHENS HYDRAULIC PRESS SYSTEM Filed April 15, 1945 2 Sheets- Sheet 2 Illa grime/rm Patented Sept. 17, 1946 UNlTED STATES ATENT OFFICE Application April 13, 1945, Serial No. 588,221

Hydraulic Control This invention relates to a hydraulicsystem, more particularly to an automatic cycling system for the control and operation of hydraulic machinery using a plurality of operating cylinders.

It is a general object of the present invention to provide a novel hydraulic system including automatic control valves for causing the operation of a plurality of control cylinders sequentially and cyclically. i

More Particularly it is an object of the invention to provide a hydraulic system for operating mechanism similar to forming presses and including automatic pressure actuated valves adapted to deliver fluid first toa die closing cylinder, then to a forming plunger cylinder and to provide for maintaining pressure on the die closing cylinder by deriving this pressure from the exhaust side of the forming plunger cylinder, thus eliminating the usual accumulator.

An im ortant feature of the invention comprises the use of an automatic cycling valve together with a flow diverting valve whereby the die closing cylinder, the forming plunger cylinder and the knock-out operating cylinder can be actuated cyclically and sequentially to first close the dies then project the forming plunger; then open the dies, lift the knockout plunger and simultaneously retract the forming plunger.

The system comprises an assemblage of cylinders, pistons, valves and piping and obviously the design and construction of any of the individual units is independent of the novel concept of this invention involving the system and specific arrangement of the units.

Other and further objects and features of the invention will be more apparent, to those ski led cally the fluid system for controlling the, same,

the press being shown in position for loading;

18 Claims. (Cl. 113-44) Fig. 2 is a vertical central section through the 7 press only of Fig. 1 shown in the final forming position; v Fig. 3 is a central section through a flow dihalf H of the forming die; -l2 connect-the base plate ID to and spacefrom 2 verting valve used in the hydraulic system, and Fig. 4 is a fragmentary central vertical section on an enlarged scale of the plunger head showing the air relief valve.

The present inventionwhich is concernedprimarily with hydraulic operating means and systems for presses is illustrated in conjunction with what isgenerally-termed a forming press, butit will be understood that this is merely for convenience, for the hydraulic cylinders and associated actuating system may be incorporated with numerous types of presses and other devices such as machine tools which require similar sequential operation.

Referring now to Figs. 1 and2 it will be seen that the press is built 'up about a suitable base plate It on which is rigidly secured the lower Standards or rods slide 15 is equipped with bushings It for guiding the same on "the rods 12 and carries the upper or movable die section I! which can be reciprocated from the full open position illustrated in Fig. 1

. to the fully closed position illustrated inFig- 2.

To the upper surface of the slide I5 is attached a plate I8 into which is threaded the lower end of the hollow pistonrod l9 arranged to reciprocate the slide and movable die.

Intermediate its length this hollow piston rod l9 has fixed theretoa piston 20 adapted to reciprccate ina die closing cylinder 2| which is rigidly attached 'to a cylinder head 22 secured in an aperture in the top press plate M. This head 22 is provided with appropriate packing glandsand tightening nuts as shownat 23. The upper cylinder head 24 is likewise equipped with packing glands and tightening elements since the hollow rod l9 passes out through the same and is of such a length that when the piston 20 is at the bottom of its stroke a portion of the rod extends above the upper cylinder head.

Theupper endof the hollow rod is internally threaded to receive'the externally threaded neck on the lower head 260i the cylinder 21 which is bodily carried by the hollow piston rod IS. The upper end of cylinder 2'! is closed by a suitable head 28 and a piston 29is arranged for reciprocation in the cylinder 21. It is attached to a smaller diameter piston rod 30 which has a packed fit in the cylinder head '25, extends through hollow piston rod l9 and slide l5 and is attached to a forming plunger 32 adapted 'to reciprocate in an opening 33 in the movabledie ll.

Thestationary die I l is provided with a cen- As seen in Fig. 1, withthe dies spaced apart or i open, with the forming plunger 32 etracted and the knock-out device 36 elevated, the press is ready for loading with a pre-iormed blank cylinder 42 of sheet metal having a closed "bottom and an open top. In the manipulation of the press the movable die I1 and the plunger 32 are moved downwardly simultaneously until the upper edge of the cylinder blank 42 is engaged by the shoulder 44 at the top of the recess in the movabledie. Continued movement of the die I! forces the blank to drive the knock-0ut device 36 into its recess 3! which is accomplished just as the top of the upper face of the stationary die and the lower face of the movable die close together at 45-as seen in Fig. 2.

. With these two dies held together the forming plunger is now moved downwardly and passes into theneck'of the blank, which has been filled with water to approximately the level shown at W in Fig. 1. The plunger is a-close fit into the neck of the blank and any air trapped beneath it is permitted to escape during the time the plunger is approaching the surface of 'the Water through the check valve-illustrated in Fig. 4.

"This valve unit is received in a central bore 4'! in the forming plunger 32 and comprises a housing 48 and a plunger 49 centrally bored as at 50 and having a sliding fit in the passage 5| in the housing. A snap ring 52 engaging the back face of the housing prevents the plunger from dropping' out. The central bore '50 of the plunger intersects radial bore 53 just beneath the head 54 thereof which isof the poppet type and engages the seat 55 when closed. The relatively slow movement of theforming plunger permits air to beforced out through bores 53 and 50 into the central passage 41 from which it passes upwardly into the bore 56 at the lower-end of the smaller pistonrod 'ell-which-bore is connected with radial bores 58. Air 'is thus delivered inside of the hollow piston rod I!) which is provided with radial bores 69, normally closed in the packing 23 when the piston 20 is at the top of its stroke, but uncovered, as clearly seen inlFig.2, when the dies are closed. When'the plunger encounters the predetermined quantity of liquid in the blank, this material, being more dense thanair, immediately closes the valve and the forming plunger is moved on down, displacing the liquid and distending the blank until itengages the Walls of the die which cause it to assume the desired shape as shown in Fig. 2 as determinedby the configuration :of the die recesses.

The next operation consists in separating the dies II and 11 and simultaneously raising the knock-out device 36 to push the finished blank out of the lower die for later manual removal. While'the dies are reaching their maximum separation'the forming plunger 32 is being withdrawn and the device is ready to have the form blank removedand' a :fresh one inserted for the next similar operation.

It is the. purpose of the present invention to provide a hydraulic system for automatically cycling the press mechanism to carry out the sequence of events just described, requiring, on the part of the operator, but the simple pushing of a button to start each complete cycle which thereafter is carried out entirely automatically.

The hydraulic mechanism includes a tank H! for suitable hydraulic liquid, a continually operating positive displacement pump H, a plurality of valves and suitable piping. Fluid is taken by the pump and delivered by pipe 12 to an automatic cycling valve 13 of the type disclosed in my ,copending application for Full cycle hydraulic valve, Serial No. 556,191, filed September 28, 1944, which is provided with a pipe return 1 5 to the tank and with delivery pipes 15 and 76. This valve is also equipped with internal bypass means so that when in the neutral position with no liquid being delivered for use the pump merely circulates oil freely from the tank through the valve 1.3 and pipe 14 back to the tank. When it is desired .to-operate th forming press the attendant pushes the button 133 which automatically conditions the valve to close the bypass and deliver fiuid from the pump into the pipe line 15. At

' the same time the cycling valve connects pipes 16 and 14 so that liquid being returned from certain cylinders of the press is conducted to the tank 79.

Liquid in pipe 15 under suitable high pressure ilows to the diverting va1ve8il, better shown in Fig. 3, which causes the liquid to'be delivered only to pipe 8|, hence through check valve 82 to pipes 83 and 84. Pipe 83 delivers liquid into cylinder 2| above or to the outer face of piston 20 and causes the hollow piston rod to move downwardly for the die closing operation. Liquid endeavoring to enter pipe 84 merely serves to maintain the piston 29 at the outer end of its stroke, insuring against unwarranted relative movement between the movable die'and the forming plunger.

Liquid is continuously delivered until the dies are closed when the resistance causes the pressure tobuild up to such an extent that diverting valve 86 disconnects line 15 from line 8i and connect the former to line '85 which delivers liquid to line 86 connected to the top head of cylinder 21 and pressure is applied to the outer face of piston 29 to advance the forming plunger on its working stroke. a

During the time that piston 23 is being forced downwardly the liquid beneath it is being. discharged through pipe line 88 into pipe line it 1 and thence by valve '53 and pipe '54 to the tank.

During the latter part of the stroke of the upper "die the knock-out device 36 and its piston 39 is driven downwardly by the action of the blank and liquid is forced out of cylinder .9 tlnough pipe 89, joining pipe 76, and finds its way back to the tank as just described. V

The cycling valve 13 is so constructed that, as for instance, when the resistance to movement of plunger 32 is such that the fluid pressure builds up within this valve to a predetermined point, it automatically reverses itself andithereafter delivers high pressure liquid from pipe 12 to pipe 15 and connects pipe 15 to returnpipe 14. This now reverses the operation of the. press, for "liquid is now delivered beneath or on the inner side of piston 20 which moves upwardly carrying with it the movable die. Liquid discharged from above piston it by this operation cannot return from pipe 83 to pipe 8! because of check valve 82 so that it move upwardly through 84 and supplies the liquid for lifting piston 29 which retracts the forming plunger during the upward movement of the die ll. A

larger volume of liquid is delivered from the upper or outer side of piston 20 than can be received beneath piston 29 and some of it returns via pipe 9| and relief valve 92 to the tank through pipe 93.

As the die and forming plunger are lifted the load is removed from the knock-out device 36 and liquid passing from pipe 16 into pipe 89 elevates piston 39 and with it the plunger 35 and lifts the finished product from the die. When all of the pistons reach their uppermost position, continued application of pressure from the pump causes the cycling valve 13 to reset itself to neutral, whereby the excess pressure from the pump is returned through the bypass to pipe M and the button 133 is positioned in readiness for the next operation. While the piston 29 is being lifted, a just described, liquid is discharged from above it through pipe 86, check valve 95, pipe 15, valve 13 and pipe 14 to the tank.

It has been found by experiment that the pressure needed to form the work piece is of the order of four times that necessary to hold the dies together during the forming operation. This then requires a particular setting of the several valves mentioned in the system. It is assumed that 60 p. s. i. will be required to hold the dies together while the forming plunger is moving down, and it will be seen that this pressure is obtained from the underside of piston 29 via pipe 84 and pipe 83. Part of the pressure applied to the top of piston 29 is endeavoring to discharge liquid from beneath it and creates a pressure which operates to hold plunger 20 down. Since there can be no flow of liquid from beneath piston 29 to above piston 20 because the system is full of liquid and the piston 28 is at the bottom of its stroke, as it is before piston 29 starts to move down, the discharging liquid beneath 29 follows the pipes 84, 9| and discharges through the relief valve 92 which is set to discharge at the said 60 p. s. i. The 240 pounds necessary to operate the piston 29 is achieved by setting the relief valve which is built into the cycling valve 13 at or above this pressure. Since but little pressure is needed to initially close the dies the diverting valve 80 is set to operate at about 50 pounds, that is, it transfers the flow from 8! to 85 when the pressure above piston 20 builds up to above 50 pounds.

The flow diverting valve 8!! is illustrated in greater detail in Fig. 3 where it will be seen to comprise a housing it!!! to which pipes 85 and 8! are attached as shown and into which leads the high pressure pipe 15. The port to which pi e 75 is attached connects to a through bore lill in which is slidably mounted a plunger H12 normally urged downwardly a ainst a stoo I03 by means of a helical pri g I04 and the closure can 5. The lower end of the plunger is hol ow at Hi6 a d open to the fluid in pipe 5. The u er end of the hollow port on has radial bores IN which. when the valve is in the position shown resti g against the stop, coo erate with chamber llltl connected to pipe line 8|. When the resistance in line 8| becomes in excess of the pressure setting of the valve, the plunger is lifted until the radial port Ill! cooperate with chamber H0 connected to p pe line 85. Whenever the pressure is above the setting of the valve, pipes 15 and 85 are connected while at other times pipes 15 and BI are connected.

I claim:

1. The combination with a press having a stationary die, a movable die and a forming plunger extending through the movable die, of a slide for said movable die, means supporting a hydraulic cylinder above said slide, a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second bydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, means to sequentially supply hydraulic liquid under pressure to the upper faces of the pistons in said first and second mentioned cylinders, and means to automatically associate the upper side of the first piston with the lower side of the second after the first piston has reached its lower limit whereby the dies are held to ether during the formin plunger stroke.

2. The combination with a press having a stationary die, a movabledie, a. forming plunger extending through the movable die, a slide for said movable die, and means supporting a hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, means to sequentially supply hydraulic liquid under pressure to the upper faces of the pistons in said first and second mentioned cylinders, means to automatically associate the upper side of the first piston with the lower side of the second after the first piston has reached its lower limit whereby the dies are held together during the forming plunger stroke and means .to maintain said associationwhen fluid is delivered beneath the first piston to withdraw the movable die and plunger.

3. The combination with a press having a stationary die, a movable die, a forming plunger extending through the movable die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, means to simultaneously supplyhydraulic liquid under pressure to the upper face ofthe piston in said first cylinder and to the under face of the second cylinder, and means automatically actuated by the first piston reaching its limit of movement to associate the supply means with the upper side of the second piston.

4. The combination with a press having a stationary die, a movable die, a forming plunger extending through the movable'die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, 3, piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, means to simultaneously supply hydraulic liquid under pressure to the upper face of the piston in said first cylinder and to the under face of the second cylinder, means automatically actuated by the first piston reaching its limit of movement to associate the supply means with the upper side of the second. piston,

and means to simultaneously maintain pressure on the upper surface of the first piston derived from the discharge from below the second piston.

5. Thecombination with a press having a stationary die, a movable die, a, forming plunger extending through the movable die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a, hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, means to simultaneously supply hydraulic liquid under pressure to the upper face of the piston in said first cylinder and to the under face of the second cylinder, means including a'diverter valve actuated by the increased liquid pressures resulting from the first piston reaching its limit of movement to associate the supply means with-the upper side of the second piston, means to simultaneously maintain pressure on the upper surface of the first piston derived solely from the discharge from below the second piston, and a relief valve associated with I said last mentioned means arranged to vent the excess liquid while maintaining a hold pressure for the movable die.

6. The combination with a press having a stationary die, a knock-out member operable therein, a movable die, a forming plunger extending through the movable die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to 7 said slide, extending through said cylinder, and

pump first to the upper face of the piston in said first cylinder and to the under face of'the piston in the second cylinder, means to automatically transfer the connection to the upper side of the second piston and to connect the upper side of thevfirst piston with the lower side of the second piston, said last mentioned connection including a relief valve whereby the dies are held together during the forming plunger stroke, and piping and valves to simultaneously vent the liquid beneath the first piston and the knockout piston when the first connection is made.

7. The combination with a press having a stationary die, a knock-out member operable therein, a movable die, a forming plunger extending through the movable die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, a piston and cylinder for said knock-out member, aipipe connecting the upper side of the first piston to the lower side of the second, a pump to continuously supply hydraulic liquid under pressure, manually actuated means to connect said pump discharge first to said pipe valve means responsive to excess pump pressure to automatically transfer the connection to .the upper side of the second piston a relief valve for said pipe whereby, the dies are held together during the forming plunger stroke, means to simultaneously vent the liquid beneath .thefirst piston and the knock-out piston when the first connection is made, and a cycling valve constructed and arranged to react to pressure increase due .to stoppage of the forming plunger to connect the pump to the underside of the first and knock-out pistons to return the parts to initial positions.

8. The combination with a press having a stationary die, a knock-out member operable therein, a movable die, a forming plunger extending through the movable die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a, hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder,a rod on said piston extending through said hollod rod and secured to said forming plunger, a piston and cylinder for said knockout member, a pipe continuously connecting the upper end of the first cylinder to the lower end of the second, a pump to continuously supply hydraulic liquid under pressure, manually actuated means to connect said pump discharge to said pipe and including a diverter valve and a check valve, said diverter valve being constructed to react to excess pressure to automatically transfer the connection to the upper side of the second piston, a relief valve for said pipe whereby the dies are held together during the forming plunger stroke, said manually actuated means being arranged to simultaneously vent the liquid beneath the first piston and the knock-out piston when the first connection is made, said manually actuated means being associated with a cycling valve means constructed and arranged to react to pressure increase due to stoppage of the forming plungerto then connect the pump to the underside of the first and knock-out pis tons to return the parts to initial positions, said check valve being between the said pipe and diverter valve whereby the liquid displaced above the first piston serves to lift the second piston and retract the forming plunger.

9. The combination with a press having a stationary die, a movable die, a forming plunger extending through one of the dies, a knock-out plunger operable in the other die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, alsecond hydraulic cylinder carried by the upper end of said hollow rod, a piston in'said second cylinder, a rod on said piston extending through said hollow rod and secured to one of said plungers, an oppositely disposed thirdcylinder, piston and rod associated with the. other plunger, a pump to continuously supply hydraulic liquid under pressure, valve and pipe means to connect said pump firstto the upper face of the piston. in said. first cylinder andto the under face of the piston in, the cylinder for the forming plunger, pressure responsive means to automatically transfer the connection to the upper side of the the forming. plunger piston and to connect the upper side of the first piston with the lower side of the second piston, said last mentioned connection includingv a reliefvalve, whereby the dies are, held together during the forming 9 plunger stroke as a result of pressure producing the forming stroke.

10. The combination with a press having a stationary die, a movable die, a forming plunger extending through one of the dies, a knock-out plunger operable in the other die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to one of said plungers, an oppositely disposed third cylinder, piston and rod associated with the other plunger, a pump to continuously supply hydraulic liquid under pressure, valve and pipe means to connect said pump first to the upper face of the piston in said first cylinder and to the under face of the piston in the cylinder for the forming plunger, pressure responsivemeans to automatically transfer the connection to the upper side of the forming plunger piston and to connect the upper side of the first pistonwith the lower side of the second piston, said last mentioned connection including a relief valve whereby the dies are held together during the forming plunger stroke as a result of pressure producing the forming stroke, and piping and valves to simultaneously vent the liquid beneath the first piston and the piston for the knock-out plunger when the first connection is made.

11. The combination with a press having a stationary die, a movable die, a forming plunger extending through one of the dies, a knock-out plunger operable in the other die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, a second hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to one of said plungers, an oppositely disposed third cylinder, piston and rod associated with the other plunger, a pump to continuously supply hydraulic liquid under pressure, valve and pipe means to connect said pump first to the upper face of the piston in said first cylinder and to the under face of the piston in the cylinder for the forming plunger, pressure responsive means to automatically transfer the connection to the upper side of the forming plunger piston and to connect the upper side of the first piston with the lower side of the second piston, said last mentioned connection including a relief valve whereby the dies are held together during the forming plunger stroke as a result of pressure producing the forming stroke, piping and valves to simultaneously vent the liquid beneath the first piston and the piston for the knock-out plunger when the first connection is made, and a cycling valve and piping associating said pump, cylinders and previous mentioned valves and piping and so constructed as to be pressure responsive to connect the pump to the underside of the first and knock-out pistons to return the parts to their initial positions,

12. The combination with a press having a stationary die, a movabl die, a forming plunger extending through one of the dies, a knock-out plunger operable in the other die, a slide for said movable die, and means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, andhaving an operating piston therein, a second hydraulic cylinder carried by the upper end of ,said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to one of said plungers, an oppositely disposed third cylinder, piston and rod associated with the other plunger, a pump to continuously supply hydraulic liquid under pressure, valve and pipe means to connect said pump first to the upper face of the piston in said first cylinder and to the under face of the piston in the cylinder for the forming plunger, pressure responsive means to automatically transfer the connection to the upper side of the formin plunger piston and to connect the upper side of the first piston with the lower side of the second piston, said last mentioned connection including a relief valve whereby the dies are held together during the forming plunger stroke as a result of .pressure producing the forming stroke, piping and valves to simultaneously vent the liquid beneath the first piston and the piston for the knock-out plunger when the; first connection is made, and a cycling valve and piping; associatingsaid pump, cylinders and previous mentioned valves and piping and so constructed as to be pressure responsive to connect the pump to the underside of thefirst and knock-out pistons to return theparts to their initial positions, said connection provided with the relief valve remaining in condition to transfer fluid from the upper side of the first piston to the underside of the forming plunger piston to retract the latter.

13. The combination with a press having a stationarydie, a movable die, a forming plunger extending through one of said dies, a slide for said movable die, means supporting a hydraulic cylinder above said slide, a rod secured to said slide, extending into said cylinder, and having an operating piston therein, asecond hydraulic cylinder, a piston in said second cylinder, a rod on said piston secured to said forming plunger, a pump to supply hydraulic liquid under pressure, piping connecting said pump to the outer face of the piston in the first cylinder, and to the inner face of the piston in the second cylinder, a pressure responsive valve in said pipin adapted to divert all the pump supply to the outer face of the .piston in the second cylinder when the first piston reaches its limit of stroke, a portion of the piping now serving to apply pressure to the outer face of the piston in the first cylinder from the inner face of the .piston in the second cylinder, and a relief valve adapted to discharge the excess liquid from the inner face of the second piston.

14. The combination with a press having a stationary die, a movable die, a forming plunger extending through one of said dies, a slide for said movable die, means supporting a hydraulic cylinder above said slide, a rod secured to said slide, extending into said cylinder, and having an operating piston therein, a second hydraulic cylinder, a piston in said second cylinder, a rod on said piston secured to said forming plunger, a pump to supply hydraulic liquidunder pressure, piping connecting said pump to the outer face of the piston in the first cylinder, and to the inner face of the piston in the second cylinder, a pressure responsive valve in said piping adapted to divert all the pump supply to the outer face of the piston in the second cylinder when the first piston reaches its limit of stroke, a portion of the piping now serving to apply pressure to areas-55 the outer face oft-he piston in the first cylinder from the inner face of the piston in the second cylinder, and a relief valve adaptedto discharge the excess liquid fromthe inner face --of the sec ond piston, said system having a'check valve bypassing the said diverter valve orthe return of liquid from the outer face of the piston in the second cylinder during the first operation.

=15. The combination with a press having a stationary die, a movable die, a forming plunger extending through one of said dies, a slide for said movable die, means supporting a hydraulic cylinder above said slide, a rod secured to said slide, extending into said cylinder, and having an operating piston therein, a second hydraulic cylinder, a piston in said second cylinder, a rod on said piston secured to said forming plunger, a pump to supply liquidunder pressure, piping connecting said pump to the outer face of the piston in the first cylinder,-andto the inner face of the pistonin the second cylinder, a pressure responsive valve in said piping adapted to divert all the pump supply to the outer face of the piston in the second-cylinder when the-first piston reaches its limit of stroke, a portion of the piping'now'serving to apply pressure to the outer face of the-piston in the first cylinder from the'inner 'face of the piston in the .second cylinder, "a relief valve adapted to dischargethe excess liquid from the inner face of the second piston, and a check valve between said portion of the piping and said diverter valve.

16. The combination with a presshaving a stationary die, a movable die, a forming plunger extending through one of said dies, a slide for said movable die, meanssupporting a hydraulic cylinder above said slide, a rod secured to said slide,

extending into said cylinder, and having an operating piston therein, a second hydraulic cylinder, a piston'in said second cylinder, a rod on said piston secured to said forming plunger, a pump to supply hydraulic liquid under pressure, piping connecting said pump to the outer face of the piston in the first cylinder and to the inner face of the piston in the second cylinder, a pressure responsive valve in said piping adapted to divert all'the pump supplytothe outer face of the pis- 'tonin the second cylinder when the first piston reaches its limit of strokaa portion of the piping now serving to apply pressure to the outer face of the piston in the first cylinder from the inner face of the piston in the second cylinder, a relief valve adapted to discharge the excess liquid from the inner face of the second piston, said system having a check valve bypassing the said diverter valve for the return of liquid from the outer face of the piston in the second cylinder during the first operation, and a check valve between said portion of the piping and said diverter valve.

17. The combination with'a press having a sta- .12 tionary die, a knock-out member operable therein, a movable die, a forming plunger extending through the movable die, a slide for said movable die, means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, and having an operating piston therein, asecond hydraulic cylinder carried by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, a piston and cylinder for said knock-out member, a pump to supply hydraulic liquid under pressure, an automatic cycling valve and piping adapted to first supply liquid from the pump to sequentially actuate the pistons in said first andsecond mentioned cylinders to close the dies and move the forming plungenpipe means to automatically associate the upper side of the first piston with the lower side of the second after the first piston has reached its lower limit whereby the dies are held together during the forming plunger stroke, said cycling valve being arranged to then supply liquid from thepump to the inner face of the piston in the first cylinder and to the knock-out cylinder, said pipe means now delivering liquid from the outer face of the first piston to the inner face of the second.

18. The combination with a press having a stationary die, a knock-out member operable therein, a movable die, a forming plunger extending through the movable die, a slide for said movable die, means supporting a first hydraulic cylinder above said slide, of a hollow rod secured to said slide, extending through said cylinder, andhaving an operating piston therein, a second hydraulic cylinder carried'by the upper end of said hollow rod, a piston in said second cylinder, a rod on said piston extending through said hollow rod and secured to said forming plunger, a piston and cylinder for said knock-out member, a pump to supply hydraulic liquid under pressure, an automatic cycling valve and piping adapted to first supply liquid from the pump to sequentially actuate the pistons in said first and second mentioned cylinders to close the dies and move the forming plunger, pipe means to automatically associate theupper side of the first piston with the lower side of the second after the first piston has reached its lower limit whereby the dies are held together during the forming plunger stroke, said cycling valve'being arranged to then supply liquid from the pump to the inner face of the piston in the first cylinder and to the knocleout cylinder, said pipe meansnow delivering liquid from the outer face of the first piston to the inner face of the second, andan adjustable relief valve associated with said pipe means.

WILLIAM T. STEPHENS. 

